Table_2_Effect of Early Weaning on the Intestinal Microbiota and Expression of Genes Related to Barrier Function in Lambs.docx

Weaning stress has been reported to impair intestinal health. The gut microbiota plays a vital role in the long-term health of the host. However, our understanding of weaning stress on gut microbiota and barrier function is very limited in livestock species, especially lambs. We investigated the effects of early weaning stress on intestinal bacterial communities and intestinal barrier function in lambs. A total of 24 neonatal male Hu lambs were randomly allocated into two groups, one weaned on day 28 and the other weaned on day 56. At 42 and 84 days, six lambs from each group were randomly selected and sacrificed. Ileal tissue and ileal digesta were collected to compare the differences in ileal microbiota and the mRNA levels of Toll-like receptors (TLRs) and tight junction proteins between the early weaning group and the control group at day 42 when the early weaning group have been weaned for 14 days, and at day 84 when the 28 and 56 days weaning groups had been weaned for 56 and 28 days, respectively. 16S rRNA gene sequencing of ileal samples revealed that the ileal microbiota was very different between the two groups, even at 84 days of age. Early weaning significantly increased alpha diversity and altered the relative abundance of several bacterial taxa. The expression of genes related to intestinal barrier function was affected by early weaning. Early weaning significantly increased ileal mRNA levels of TLR1 on days 42 and 84; TLR2, TLR4, and TLR5 on day 84; claudin1 and claudin4 on day 42; and occludin on day 84. We demonstrate that early weaning not only altered the ileal microbiota on day 42 (compared with lambs that were not weaned), but also had lasting effects on the ileal microbiota at day 84; furthermore, early weaning impacts expression levels of genes related to intestinal barrier function.

已有研究表明，断奶应激会损害肠道健康。肠道微生物群（gut microbiota）对宿主的长期健康至关重要。然而，目前对于家畜（尤其是羔羊）断奶应激对肠道微生物群及肠道屏障功能的认知仍十分有限。本研究旨在探究早期断奶应激对羔羊肠道细菌群落及肠道屏障功能的影响。本研究共选取24只新生雄性湖羊羔羊，随机均分为两组：早期断奶组于28日龄实施断奶，对照组于56日龄实施断奶。分别于42日龄和84日龄时，从每组随机选取6只羔羊实施安乐死并采集样本。采集回肠组织与回肠食糜，在两个采样时间点对比两组的回肠微生物群组成，以及Toll样受体（Toll-like receptors, TLRs）和紧密连接蛋白的mRNA表达水平：其中42日龄时，早期断奶组已完成14天断奶；84日龄时，28日龄断奶组与56日龄断奶组分别已断奶56天与28天。对回肠样本进行16S rRNA基因测序结果显示，两组羔羊的回肠微生物群结构存在显著差异，甚至在84日龄时仍如此。早期断奶可显著提升回肠微生物群的α多样性，并改变部分细菌类群的相对丰度。早期断奶会影响肠道屏障功能相关基因的表达。具体而言，早期断奶可显著提升羔羊回肠中TLR1在42日龄和84日龄时的mRNA表达水平；在84日龄时，TLR2、TLR4及TLR5的mRNA表达水平也显著上调；42日龄时，紧密连接蛋白claudin1与claudin4的mRNA表达水平显著升高；84日龄时，闭合蛋白（occludin）的mRNA表达水平显著提升。本研究证实，早期断奶不仅会在42日龄时改变未断奶羔羊的回肠微生物群结构，还会在84日龄时对回肠微生物群产生持久影响；此外，早期断奶会影响肠道屏障功能相关基因的表达水平。